Files
Anthropic-Cybersecurity-Skills/skills/hunting-for-ntlm-relay-attacks/SKILL.md
T
mukul975 efca3ec611 feat: add NIST CSF 2.0 nist_csf field to all 754 cybersecurity skills
Mapped every skill to NIST CSF 2.0 subcategory IDs (GV/ID/PR/DE/RS/RC functions)
based on subdomain and content analysis. Restores 11 skills corrupted during
prior rebase, re-enriching with ATLAS, D3FEND, NIST AI RMF, and CSF 2.0 fields.

All 754 skills now carry structured mappings for all 5 security frameworks:
- MITRE ATT&CK (in tags)
- MITRE ATLAS v5.5 (atlas_techniques)
- MITRE D3FEND v1.3 (d3fend_techniques)
- NIST AI RMF 1.0 (nist_ai_rmf)
- NIST CSF 2.0 (nist_csf)
2026-04-06 11:17:40 +02:00

2.6 KiB

name, description, domain, subdomain, tags, version, author, license, d3fend_techniques, nist_csf
name description domain subdomain tags version author license d3fend_techniques nist_csf
hunting-for-ntlm-relay-attacks Detect NTLM relay attacks by analyzing Windows Event 4624 logon type 3 with NTLMSSP authentication, identifying IP-to-hostname mismatches, Responder traffic signatures, SMB signing status, and suspicious authentication patterns across the domain. cybersecurity threat-hunting
NTLM-relay
Windows-events
Event-4624
NTLMSSP
Responder
SMB-signing
credential-access
T1557.001
Active-Directory
1.0 mahipal Apache-2.0
Application Protocol Command Analysis
Network Isolation
Network Traffic Analysis
Client-server Payload Profiling
Network Traffic Community Deviation
DE.CM-01
DE.AE-02
DE.AE-07
ID.RA-05

Hunting for NTLM Relay Attacks

Overview

NTLM relay attacks intercept and forward NTLM authentication messages to gain unauthorized access to network resources. Attackers use tools like Responder for LLMNR/NBT-NS poisoning and ntlmrelayx for credential relay. This skill detects relay activity by querying Windows Security Event 4624 (successful logon) for type 3 network logons with NTLMSSP authentication, identifying mismatches between WorkstationName and source IpAddress, detecting rapid multi-host authentication from single accounts, and auditing SMB signing configuration across domain hosts.

When to Use

  • When investigating security incidents that require hunting for ntlm relay attacks
  • When building detection rules or threat hunting queries for this domain
  • When SOC analysts need structured procedures for this analysis type
  • When validating security monitoring coverage for related attack techniques

Prerequisites

  • Python 3.9+ with Windows Event Log access or exported logs
  • Windows Security audit logging enabled (Event ID 4624, 4625, 5145)
  • Network access for SMB signing status checks

Key Detection Areas

  1. IP-hostname mismatch — WorkstationName in Event 4624 does not resolve to the source IpAddress
  2. NTLMSSP authentication — logon events using NTLM instead of Kerberos from domain-joined hosts
  3. Machine account relay — computer accounts (ending in $) authenticating from unexpected IPs
  4. Rapid authentication — single account authenticating to multiple hosts within seconds
  5. Named pipe access — Event 5145 showing access to Spoolss, lsarpc, netlogon, samr pipes
  6. SMB signing disabled — hosts not enforcing SMB signing, enabling relay attacks

Output

JSON report with suspected relay events, IP-hostname correlation anomalies, SMB signing audit results, and MITRE ATT&CK mapping to T1557.001.